REACTIONS OF VINYLSILANES WITH LEWIS ACID-ACTIVATED IODOSYLBENZENE: STEREOSPECIFIC SYNTHESIS OF VINYLIODONIUM TETRAFLUOROBORATES AND THEIR REACTIONS AS HIGHLY ACTIVATED VINYL HALIDES

Article abstract of DOI:10.1016/S0040-4020(01)86659-X

Alkenyl(phenyl)iodonium tetrafluoroborates 3 were synthesized from alkenylsilanes 1 by the reaction with iodosylbenzene and boron trifluoride-diethyl ether or triethyloxonium tetrafluoroborate.The reaction proceeds stereospecifically with retention of configuration of 1.X-ray diffraction analysis of (4-tert-butylcyclohexenyl)phenyliodonium tetrafluoroborate (3b) revealed the highly ionic structure with the distorted T-shape arrangement.Iodonium salts 3 behave like the highly activated species of vinyl iodides due to the high leaving ability of the iodine(III) substituents.Thus, a variety of substituted olefins including α-cyano and α-nitro olefins, vinyl sulfides, vinyl halides and α,β-unsaturated esters, were synthesized from 3 under mild conditions.A ligand coupling mechanism via the formation of 10-I-3 intermediate 27 containing a copper(III) ligand is proposed for the substitutions of 3 with nucleophiles.